State of Charge Control for a Fuel Cell Vehicle

The present application claims priority to European Patent Application No. 24164614.0, filed on Mar. 19, 2024, and entitled “STATE OF CHARGE CONTROL FOR A FUEL CELL VEHICLE,” which is incorporated herein by reference in its entirety.

The disclosure relates generally to fuel cell vehicles. In particular aspects, the disclosure relates to state of charge control for a fuel cell vehicle. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle.

In current fuel cell technologies utilized in vehicles, a significant portion of the energy input into the fuel cell is converted into thermal energy. Unlike traditional diesel engines, which operate at higher temperatures and expel a considerable amount of heat energy via exhaust, fuel cells function at lower temperatures and emit significantly less heat energy through their exhaust systems. Consequently, the cooling system of a fuel cell electric vehicle (FCEV) must dissipate a large amount of thermal energy to maintain the fuel cell at an optimal operating temperature. Should the cooling system extract excessive thermal energy, the fuel cell may be required to derate, that is, reduce its power output to prevent overheating. This necessity for enhanced cooling renders FCEVs particularly susceptible to challenges during high-power output operations under standard ambient temperature conditions.

According to a first aspect of the disclosure, there is provided a computer system comprising processing circuitry configured to: simulate a power output profile for an upcoming route for a vehicle propelled by an electric machine powered by a fuel cell system and an electrical energy storage system chargeable by the fuel cell system, acquire cooling efficiency information of a cooling system of the vehicle arranged to cool the fuel cell system, calculating, for an upcoming increase in power demand according to the power output profile, the power output available from the fuel cell system without overloading the cooling system according to the cooling efficiency information, determine a control strategy for energy stored in the electrical energy storage system from a present position to the end of the route, the control strategy comprises, for each upcoming increase in power demand, at least one time slot for charging the electrical energy storage system using the fuel cell system to a first energy level that ensures that the upcoming increase in power demand is met by the calculated power output available from the fuel cell system and the first energy level of the electrical energy storage system, execute the control strategy, and update the simulation and the control strategy while the vehicle is travelling the route.

The first aspect of the disclosure may seek to decrease the risk of derating the fuel cell system. That is, first aspect seeks to provide more efficient use of the fuel cell system in such a way that lowering the power output due to insufficient cooling is avoided.

Optionally in some examples, including in at least one preferred example, the upcoming increase in power may be determined to ensure that the vehicle speed can be substantially maintained throughout the road section corresponding to the upcoming increase in power. A technical benefit may include more uniform driving through the road section. Furthermore, the vehicle speed is a straight forwards parameter for the simulation of the power profile.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: acquire input data including a speed profile for the route, an altitude profile for the route, and vehicle characteristic data, simulate the power output profile based on the acquired input data. A technical benefit may include more accurate simulation of the power output profile since more input data is used.

Optionally in some examples, including in at least one preferred example, the input data further includes map that comprising weather input data. A technical benefit may include even further improved accuracy in the simulation of the power output profile due to that also weather conditions are considered in the simulation. Furthermore, using weather data as input allows for taking the ambient conditions into account thereby improving the control strategy further. It can be especially useful when the weather conditions change over the course of the planned route.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: transmit, via a wireless communication device, the control strategy to other vehicles on the same route. A technical benefit may include improved control strategies also based on historical data from other vehicles. Furthermore, in scenarios involving autonomous or semi-autonomous vehicles, sharing control strategies facilitates the optimization of the entire fleet's operation, allowing for more efficient route planning and energy management on a system-wide level. In addition, using data from other vehicles improves decision making in developing the control strategy.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: determine an upcoming time period during the route where the fuel cell system is in an idle state, and include, in the control strategy, time slots prior to the idle state for preparing the electrical energy storage device to be able to receive idle energy from the fuel cell system as charging energy. A technical benefit may include further improved control strategy that also considers idle states of the fuel cell system. Taking idle state time slots into account improves energy harvesting, thus preparing the electrical energy storage system (e.g., battery) to receive otherwise wasted energy, the system ensures that energy is harvested and stored rather than dissipated as heat or wasted. Using idle energy to charge the electrical energy storage system, the need for the fuel cell system to operate at higher power levels solely to charge the electrical energy storage system during periods of high demand is reduced.

Optionally in some examples, including in at least one preferred example, the processing circuitry is further configured to: prior to departure, providing data of a present energy level of the electrical energy storage system as input to the simulation. A technical benefit may include that input concerning energy level in the electrical energy storage system improves the accuracy of the simulation and control strategy. That is, the simulation gets information of the initial state of the electrical energy storage system.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: determine, from the simulation and prior to departure, a required energy level in the electrical energy storage system, and set a charge level of the electrical energy storage system to the required level during pre-departure charging. A technical benefit may include, in case of charging is available, the charge level may be adjusted to improve the accuracy of the control strategy further.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: evaluate the simulated power output profile in view of the control strategy, determine a measure of the outcome of the control strategy indicating the success rate of the control strategy, provide an output of the measure. A technical benefit may include that future simulations can be improved by evaluating the outcome of previous simulations. That is, a technical advantage of evaluating the control strategy's performance and providing a measure of its success rate may lay in enabling a feedback loop that supports continuous improvement, data-driven decision-making, and operational transparency.

Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: adapt simulation parameters based on the outputted measure. A technical benefit may include improved simulations and therefore also reduced risk of derating of the fuel cell system.

There is further provided a vehicle comprising the computer system.

According to a second aspect of the disclosure, there is provided a computer-implemented method, comprising: simulating, by processing circuitry of a computer system, a power output profile for an upcoming route for a vehicle propelled by an electric machine powered by a fuel cell system and an electrical energy storage system chargeable by the fuel cell system, acquiring, by the processing circuitry, cooling efficiency information of a cooling system of the vehicle arranged to cool the fuel cell system, calculating, by the processing circuitry, for an upcoming increase in power demand according to the power output profile, the power output available from the fuel cell system without overloading the cooling system according to the cooling efficiency information, determining, by the processing circuitry, a control strategy for energy stored in the electrical energy storage system from a present position to the end of the route, the control strategy comprises, for each upcoming increase in power demand, at least one time slot for charging the electrical energy storage system using the fuel cell system to an energy level that ensures that the upcoming increase in power demand is met by the fuel cell system and an electrical energy storage system, executing, by the processing circuitry, the control strategy, and updating, by the processing circuitry, the simulation and the control strategy while the vehicle is travelling the route. The second aspect of the disclosure may seek to decrease the risk of derating the fuel cell system. That is, second aspect seeks provides more efficient use of the fuel cell system in such a way that lowering the power output due to insufficient cooling is avoided.

Optionally in some examples, including in at least one preferred example, the upcoming increase in power is determined to ensure that the vehicle speed can be substantially maintained. A technical benefit may include more uniform driving through the road section. Furthermore, the vehicle speed is a straight forward parameter for the simulation of the power profile.

Optionally in some examples, including in at least one preferred example, the method may further comprise: acquiring, by the processing circuitry, input data including a speed profile for the route, an altitude profile for the route, and vehicle characteristic data, and simulating, by the processing circuitry, the power output profile based on the acquired input data. A technical benefit may include more accurate simulation of the power output profile since more input data is used.

Optionally in some examples, including in at least one preferred example, the method may further comprise: transmitting, by the processing circuitry, via a wireless communication device, the control strategy to other vehicles on the same route. A technical benefit may include improved control strategies also based on historical data from other vehicles.

Optionally in some examples, including in at least one preferred example, the method may further comprise: determining, by the processing circuitry, an upcoming time period during the route where the fuel cell system is in an idle state, and including, by the processing circuitry, in the control strategy, time slots prior to the idle state for preparing the electrical energy storage device to be able to receive idle energy from the fuel cell system as charging energy. A technical benefit may include further improved control strategy that also takes into account idle states of the fuel cell system.

Optionally in some examples, including in at least one preferred example, the method may further comprise: prior to departure, providing, by the processing circuitry, data of a present energy level of the electrical energy storage system as input to the simulation. A technical benefit may include that input concerning energy level in the electrical energy storage system improves the simulation and control strategy.

Optionally in some examples, including in at least one preferred example, the method may further comprise: determining, by the processing circuitry, from the simulation and prior to departure, a required energy level in the electrical energy storage system, and setting, by the processing circuitry, a charge level of the electrical energy storage system to the required level during pre-departure charging. A technical benefit may include, in case of charging is available, the charge level may be adjusted to improve the control strategy further.

Optionally in some examples, including in at least one preferred example, the method may further comprise: evaluating, by the processing circuitry, the simulated power output profile in view of the control strategy, determining, by the processing circuitry, a measure of the outcome of the control strategy indicating the success rate of the control strategy, providing, by the processing circuitry, an output of the measure. A technical benefit may include that future simulations can be improved by evaluating the outcome of previous simulations.

Optionally in some examples, including in at least one preferred example, the method may further comprise: adapting, by the processing circuitry, simulation parameters based on the outputted measure. A technical benefit may include improved simulations and therefore also reduced risk of derating of the fuel cell system.

There is further provided a computer program product comprising program code for performing, when executed by the processing circuitry, the method of the second aspect.

There is further provided a non-transitory computer-readable storage medium comprising instructions, which when executed by the processing circuitry, cause the processing circuitry to perform the method of the second aspect.

The disclosed aspects, examples (including any preferred examples), and/or accompanying claims may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art. Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.

There are also disclosed herein computer systems, control units, code modules, computer-implemented methods, computer readable media, and computer program products associated with the above discussed technical benefits.

The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

Fuel cells operate at a relatively low temperature and output only a small amount of heat through their exhaust. This places a high demand on the cooling system of the fuel cells. If the cooling system exceeds its capability, the fuel cell must reduce (derate) its power output to avoid overheating. The examples disclosed here predictably decrease the risk of derating by simulating the power needs for a driving cycle of a fuel cell electric vehicle before departure. The output of the simulation is used to adjust and control the stored energy in the onboard electrical energy storage system of the vehicle, ensuring the vehicle can meet upcoming power need. Additionally, the prediction of power output can be performed while the vehicle is driving the cycle to ensure the latest and most precis prediction of future need of power output. This prediction can be run either onboard or offboard and communicated to the vehicle.

is an exemplary system diagram of a computer systemfor predictively reducing the risk of derating a fuel cell system according to an example comprising a processing circuitry.

In this example, the computer systemis comprised in a vehiclepropelled by an electric machinepowered by a fuel cell systemand an electrical energy storage systemrechargeable by the fuel cell system.

A cooling systemis configured to cool the fuel cell system. The cooling systemmay be a liquid cooling system. The cooling systemis associated with a cooling efficiency.

The processing circuitryis configured to acquire cooling efficiency informationconcerning the efficiency of the cooling systemand information concerning an upcoming route. The upcoming routeinformation may be acquired from a database of known scheduled routes for the vehicle, or the routemay be predicted based on historical routes travelled at given times.

The processing circuitryis configured to simulate a power output profile for an upcoming routefor a vehiclepropelled by an electric machinepowered by a fuel cell systemand an electrical energy storage systemchargeable by the fuel cell system. The power output profile provides the power required at different locations along the upcoming route. The processing circuitrymay acquire input dataincluding a speed profilefor the route, an altitude profilefor the route, and vehicle characteristic data, and simulate the power output profile based on the acquired input data. The vehicle characteristic data includes for example rolling resistance and air drag coefficients.

In addition, the input datamay further include a mapcomprising weather input data. That is, to provide an accurate simulation of the power output profile, the processing circuitrymay take, as input, the speed profilefor the route, an altitude profilefor the route, vehicle characteristic data, and weather data.

The processing circuitrysimulates the power needed at different instances along the route, by modelling the core essential parts of the vehicle that contributes to power consumption, such as the complete drivetrain, auxiliary loads and PTO (Power Take Off). Parameters such as the total weight of the vehicle, aerodynamic drag coefficient and the trucks rolling resistance are preferably considered as well. This vehicle model is then used to calculate the power consumption for the road/route topography and speed.

The processing circuitry further acquires the cooling efficiency informationof the cooling systemof the vehicle arranged to cool the fuel cell system. The cooling efficiency informationmay be the maximum cooling efficiency of the cooling system.

The processing circuitrycalculates, for an upcoming increase in power demandaccording to the power output profile, the power output available from the fuel cell system without overloading the cooling system according to the cooling efficiency information. That is, the power output available is that maximum power which does not produce more heat than the maximum cooling efficiency of the cooling system can provide.

The upcoming increase in power may be for climbing a hill and may be determined so that the upcoming increase in power is determined to ensure that the vehicle speed can be substantially maintained throughout the road section corresponding to the upcoming increase in power. That is, the hill can be climbed at a speed which the fuel cell power can maintain throughout the climb.

The processing circuitrydetermines a control strategyfor energy stored in the electrical energy storage system from a present position to the end of the route. The control strategycomprises, for each upcoming increase in power demand, at least one time slotfor charging the electrical energy storage systemusing the fuel cell systemto a first energy levelthat ensures that the upcoming increase in power demandis met by the calculated power output available from the fuel cell system and the first energy level of the electrical energy storage system.

The processing circuitryexecutes the control strategyin a vehicle control system. Furthermore, the processing circuitryupdates the simulation and the control strategywhile the vehicleis travelling the route. In other words, the simulation and control strategyis continuously adapted to the present ambient conditions of the vehicle.

The vehiclecomprises a wireless communication deviceconfigured to provide communication capabilities with a remote serverand/or other vehicles. The wireless communication devicemay be configured for any type of wireless communication technology suitable such as Wi-Fi, mobile networks, radio communications etc. The processing circuitrymay transmit, using the wireless communication device, the control strategyto other vehicleson the same route.

In some situations, the fuel cells of the fuel cell system are in an idle state. For example, when no traction power is needed, which may be the case when travelling in a down slope the fuel cell system may be set to an idle state. However, even in the idle state, the fuel cell system output some power, in the range of 20-60 kW. This power is preferably absorbed by the electrical energy storage system. Idle states of the fuel cell systemmay be included in the control strategy which improves the energy harvesting efficiency of the system. The processing circuitry may be further configured to determine an upcoming time period during the route where the fuel cell system is in an idle state. For example, the time periods may be when travelling downhill, which information may be extracted from the route data. The processing circuitryincludes, in the control strategy, time slots prior to the idle state for preparing the electrical energy storage systemto be able to receive idle energy from the fuel cell system as charging energy. In other words, as the vehicle executes the control strategy and approaches an idle state time slot, the electrical energy storage system is discharged, preferably through providing traction power, such that it can receive, and be charged by the power from the fuel cell systemduring its idle state.

To initiate the simulation and to provide initial input, the processing circuitryprovides, prior to departure, data of a present energy level of the electrical energy storage system. In situations where charging of the electrical energy storage systemis available, the processing circuitrymay determine, from the simulation and prior to departure, a required energy level in the electrical energy storage system. The required energy level, such as state of charge, SoC, may be set so that excess energy can be absorbed from the fuel cell systemand/or regenerative braking, especially during early occurring events requiring absorption of energy. The processing circuitrysets a charge level of the electrical energy storage systemto the required level during pre-departure charging.

The simulation and consequently also the control strategy may be improved over time. For this, the outcome of the simulation can be evaluated in view of the executed control strategy to determine if there was any risk of overloading the cooling systemand derating the fuel cell systemand the vehiclelose speed. The processing circuitrymay thus evaluate the simulated power output profile in view of the control strategy. The processing circuitrydetermines a measure of the outcome of the control strategy indicating the success rate of the control strategy and provides an output of the measure. The measure may be the number of occasions where derating was at risk, or where it actually occurred. No derating occasions is the aim of the control strategy and the highest success.

The processing circuitrymay adapt simulation parameters based on the outputted measure. For example, the power split between fuel cell systemand electrical energy storage system, the so-called equivalence factor, may be varied, the rolling resistance of the vehicle may be adjusted, the cooling efficiency may be updated, or vehicle control parameters such as speed at cruise control.

are each a set of graphs to describe a planned route, fuel cell output power, and the state of charge, SoC of the electrical energy storage system. The top graphis the altitude profilefor the planned route which to some extent reflect the power need, the second graphis a speed profilefor the vehicle, the third graphis the fuel cell power output for the fuel cell system of the vehicle, the fourth graphis the cooling system temperature also indicating a maximum allowed temperature, and the bottom graphis the SoC of the electrical energy storage system.

illustrates the graphs for a prior art system without an efficient control strategy for the SoCof the battery. The SoC of the battery is very low when the vehiclereaches an area, uphill in this case, where high power is demanded at time t. Since the SoC is very low at the time twhen the high-power demand areais reached, the fuel cell system has to deliver all the power needed to climb the hill, and the power outputfrom the fuel cell system increases rapidly at time t. This causes the cooling system temperatureto increase rapidly and eventually reach the maximum allowed temperature at time t. This is especially prominent in high ambient temperatures. Since the cooling system cannot keep up, the fuel cell system has to derate, i.e., reduce its power output at time twhich also causes a reduction in speed. In other words, the vehiclewill have to drive slowly up the hill, reflected in the decreased speedafter time twhen the fuel cell system has reduced its power output.

illustrates the graphs,,,,but when the herein described methods are used. Due to the simulated power output profile, the computer system is aware of the upcoming high-power demand. The computer systemcan calculate, for the upcoming high-power demandhow much power the fuel cell systemcan provide without overloading the cooling system. The control strategy for SoCof the electrical energy storage systemthat is prepared includes a time slot dTwhere the fuel cell systemincreases its power outputin preparation for the high-power demand. This charges the electrical energy storage systemto a higher SoC, during time slot T. Before reaching the high-power demand area, the power output from the fuel cell systemis reduced, at time here indicated as time T, to allow recovery for the cooling systemprior to reaching the high-power demand area. That is, the temperature of the cooling system reduces at time T.